Outcome-based education is one of the most significant global developments in medical education in recent years. This paper presents four case studies of outcome-based education from medical schools in different parts of the world; Scotland; USA; Pakistan; and Singapore. The outcome-based curricula have either been in place for some time, are evolving or are at the planning proposal stage. The outcomes, change process and implementation of the outcome-based approach are described. Variation in the extent to which each medical school has implemented outcome-based education is discussed and key points for successful implementation are highlighted. This paper is based on the pre-conference symposium "outcome-based curricula: global perspectives" presented by the authors at the 4th Asia Pacific Medical Education Conference (APMEC) in Singapore, 8-11 February, 2007.